Use the OPL3 YMF262

The YMF262 is inside the FPGA of some machines

The F256 machines, except the F256Jr., have in their Beatrix FPGA a YMF262 capable of Yamaha OPL3 that uses up to 36 operators. You can also use it in compatible OPL2 that uses a subset of up to 18 operators

F256 registers for 6502, 65816, 6809(?) cores

Register Name	Address	Description
OPL_ADDR_L	0xD580	Register for addressing ports 0x000 to 0x0FF
OPL_DATA	0xD581	Data register for all ports
OPL_ADDR_H	0xD582	Register for addressing ports 0x100 to 0x1FF

Usage:

When targetting a port in the 0x000 - 0x0FF range, send the port byte to 0xD580, then its data byte to 0x581.

When targetting a port in the 0x100 - 0x1FF range, send the port byte masked with 0x0FF to 0xD582, then its data byte to 0xD581.

Example 1: to star the chip using port 0x01, send 0x01 to 0xD580, then 0x01 to 0xD581.

Example 2: to enable OPL3 using port 0x105, send 0x05 to 0xD582, then 0x01 to 0xD581.

Chip wide ports

Port Name	Port Address	Description	B7	B6	B5	B4	B3	B2	B1	B0
Test Register / Waveform Select Enable	0x01	Must be used to "start the chip"	Test Register		Wave Select Enable	Test Register
		Set all Test Register bits to 0 to start the chip. B5 clear = all sine waves B5 set= enables wave choices in 0xE0-F5
Timer 1 Count	0x02	8bit timer with resolution of 80 us.
		If overflow occurs, status register is set and preset value is loaded
Port Name	Port Address	Description	B7	B6	B5	B4	B3	B2	B1	B0
Timer 2 Count	0x03	8bit timer with resolution of 320 us.
		If overflow occurs, status register is set and preset value is loaded
IRQ-Reset/Mask/Start	0x04	Timer controls	Reset	T1Mask	T2Mask	-	-	-	T2Start	T1Start
		B7 resets and IRQ flags status reg and ignore all others when this is set B6 timer 1 mask. status reg is not affected in overflow B5 timer 2 mask. same for timer2 B1 Timer 2 start. timer on/off B0 Timer 1 start, same
Port Name	Port Address	Description	B7	B6	B5	B4	B3	B2	B1	B0
Four-Operator Enable	0x104	Sets up four-operator channels	-	-	ChB	ChA	Ch9	Ch2	Ch1	Ch0
		When fully set 0, 18 two-operator pairs are formed. When non-zero, four-operators are formed at specific locations B5: channels 11-14 (decimal) are grouped B4: channels 10-13 B3: channels 9-12 B2: channels 2-5 B1: channels 1-4 B0: channels 0-3
OPL3 Mode Enable	0x105	enables OPL3 extensions	-	-	-	-	-	-	-	Enable
		set B0 to enable 36 operators, 4-OP synth, 8 waveforms, stereo output. When cleared, OPL2 is enabled.
Port Name	Port Address	Description	B7	B6	B5	B4	B3	B2	B1	B0
Tremolo/Vibrato/Percussion	0xBD	Bits 0-4 are treated as key-on/key-offs.	Tre	Vib	Per	BassDrum	SnareDrum	Tom-Tom	Cymbal	Hi-Hat
		B7 and B6 set = more present effect. When using B0-B4, key-on in channels 6,7,8 and their fnums have to be cleared! Their ADSR must be appropriate This register is only used in OPL2 lower half, it does not affect higher half OPL3.

Channel wide ports

to be continued

Operator wide ports

to be continued